1. Field of the Invention
The invention pertains to shuttleless looms of the type which insert each pick of weft by two reciprocating elements that are commonly referred to as the inserting and extending carriers. For a detailed description of one form of such loom, attention is hereby directed to U.S. Pat. No. 2,604,123. The insertion of weft, drawn from an outside source, into sheds of warp threads by means of opposed carrier members does not result in forming selvage at either or both sides of the fabric and more particularly, the invention pertains to an improved device for use in such looms which will form a so-called twisted or leno type selvage along the edge of fabric as it is formed.
2. Description of the Prior Art
In looms wherein weft is not interwoven with warp threads as in fly shuttle looms to form normal selvages at both sides of the fabric, it is common practice to form a twisted or leno selvage by such a device as disclosed in the teachings of U.S. Pat. No. 2,710,631. This form of device produces a twisted or leno selvage by feeding and shedding two selvage threads by a rotatable disc member which twists them and the pick of weft together at each or spaced shed changes. The selvage threads are drawn from supply spools that are carried on the rotatable disc which requires a separate means of drive such as belts, chains or gearing operatively interconnecting said disc with any suitable source of rotary motion on the loom.
The type of selvage mechanism disclosed in U.S. Pat. No. 2,710,631 has performed its intended function satisfactorily on looms forming weaves which require from two to 10 harnesses.
With an increase in the number of harnesses in a loom for the purpose of forming more complex weaves, such as by dobby weaving necessitates a greater number of harnesses and can increease the number to as high as 24 harnesesses per loom.
An increase in the number of harnesses per loom necessitates substantially more space to accommodate said harnesses and requires, what is considered, undesirable changes to the disc type selvage mechanism in order to utilize the same.
The additional space required by an increase in the number of harnesses requires that the rotatable disc on which the selvage thread spools are carried be mounted further rearwardly on the loom. To do this the disc must be increased in diameter so that the selvage thread spools can be mounted further apart in order to form the desired angular opening of the selvage threads and conform generally to the shed opening formed by the warp threads so as to receive the end of a pick therebetween. Additionally the rotatable disc is provided with draw springs or so-called spring take-up arms which are operatively associated with each spool of selvage thread carried on said disc and serve to prevent slack in the selvage thread when their respective spools come into horizontal alignment while being rotated with said disc. These spring take-up arms are caused to move to a position which takes up the slack of their respective selvage thread and when relocated rearwardly to accommodate more harnesses would also have to be made larger like that of the disc. Each spring take-up arm is operatively associated with a single selvage thread and the combination of being made larger and the relative distance it must move to the position to perform its function coupled with the fact that it must assume said position more quickly by comparison would in many instances be detrimental to the selvage thread. Additionally the added space required by an enlarged disc and moving the same further rearwardly would be objected to as being too closely situated to certain elements of a loom such as the automatic pick finder as well as the many driving connections between the dobby and the harnesses that would make the assessibility to these and other devices on the loom difficult.
The selvage forming device comprising the invention would create none of the problems described above and can satisfactorily perform its intended function in looms operating with either the minimum or maximum number of harnesses therein.